This invention relates to a disposable diaper for absorption and containment of body fluids discharged thereon.
Japanese Patent Application Disclosure No. 1999-188056 describes a disposable diaper comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between these two sheets. Configurationally, this diaper of prior art comprises, as viewed in its longitudinal direction, a front waist region, a rear waist region and a crotch region extending between these front and rear waist regions. In the foregoing Disclosure, the diaper is described to be characterized in that there is provided an elastic member extending across a middle zone of the core in the longitudinal direction between the front and rear waist regions. This elastic member is disposed between the backsheet and the core and secured under tension to the backsheet. In the crotch region of the diaper, a tensile force of the elastic member biases the middle zone of the core to rise against a wearer""s crotch with transversely opposite side zones of the core except the middle zone remaining in a slackened state. Thus the crotch region presents its cross-section of an inverted V-shape so that the core may have its transverse dimension in the crotch region substantially reduced. In this way, any remarkably irregular deformation of the crotch region can be avoided and an efficient absorption of body fluids into the core can be ensured even when the crotch region of the diaper put on the wearer""s body is tightly held between the wearer""s thighs.
With the diaper described in the foregoing Disclosure, the transversely opposite side zones of the core are not biased by the elastic member to rise and therefore the body fluids discharged on the diaper tend to flow down from the middle zone toward the side zones of the core. The amount of body fluids having reached the side zones of the core may leak sideways out from the crotch region. Certainly, the diaper described in the foregoing Disclosure is provided in the vicinity of the side zones of the core with leak-barrier cuffs as barriers against such leak of body fluids. However, so far as the transversely opposite side zones of the core are not biased by the elastic member to rise, it is apprehended that free side edges of the respective cuffs might improperly rise, i.e., slant or collapse outward laterally of the diaper as the diaper is put on the wearer""s body. Consequently, there is an apprehension that the leak-barrier cuffs could not fulfill their desired function.
It is an object of this invention to provide a disposable diaper improved so that the transversely opposite side zones of the core are not slackened downward even when the middle zone of the core rises under the tensile force of the elastic member extending in the longitudinal direction between the front and rear waist regions and thereby any sideway leakage of body fluids can be reliably prevented.
According to this invention, there is provided a disposable diaper comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between the topsheet and the backsheet to define a front waist region, a rear waist region and a crotch region extending between the front and rear waist regions, the diaper further comprising a first elastically stretchable member lying in a middle zone of the core and extending longitudinally of the diaper between the front and rear waist regions and being disposed between the backsheet and the core and secured under tension to the backsheet, and a pair of second elastically stretchable members which lie in transversely opposite side zones of the core and extending longitudinally of the diaper between the front and rear waist regions are disposed between the backsheet and the core and secured under tension to the backsheet.
The disposable diaper according to this invention has the crotch region adapted to be curved with the W-shaped cross-section and thereby to have its transverse dimension substantially reduced so that any irregular deformation of the crotch region may be reliably avoided even when the crotch region of the diaper put on the wearer""s body is tightly held between the wearer""s thighs.
The transversely opposite side zones of the core are not slackened downwardly of the diaper but lifted upwardly of the diaper under the tensile force of the second elastic members generated as these elastic members are stretched as the diaper is put on the wearer""s body. In this way, the side zones of the core form the barriers against the discharged body fluids and reliably prevent the body fluids from leaking sideways.
In the case of the diaper provided with the leak-barrier cuffs, the fixed side edge portions of the respective cuffs lie in the vicinity of the side zones of the core lifted up under the tensile force of the second elastic members. This unique placement ensures that the free side edge portions of the cuffs can be erected in postures substantially vertical or slightly slanted inward laterally of the diaper. In this way, the free side edge portions of the cuffs can be prevented from collapsing outwardly of the diaper. The free side edge portions of the cuffs are adapted to be erected around lines defined in the vicinity of the side zones of the core. This means that the cuffs will be able to fulfill their leak-barrier function even when the cuffs are of the arrangement in which a distance between the fixed side edge portion and the associated free side edge portion is relatively small.